The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.
An LED has many merits including less power consumption, semipermanently long lifetime, brightness characteristic comparable to that of a conventional fluorescent light, and the like, and hence it is a growing trend that a considerable research is performed on the LED around the globe and the LED is steadily and widely used as a lighting source, i.e., an LED light, which is likely to replace the fluorescent light.
The fluorescent light is generally a sort of mercury discharge tube having a negative resistance characteristic, which necessitates a stabilizer as a device for stably maintaining a turn-on state after turning it on by inducing a discharge start of the fluorescent light. The stabilizer serves to apply a high voltage for starting the discharge initially required to turn on the fluorescent light and supply stable voltage and current to the fluorescent light after turning it on.
Unlike the fluorescent light, the lighting using the LED is promptly operable by constant voltage and current without such a component as the stabilizer, and has an advantage that a power required for the LED light to generate a level of illumination equivalent to that of the fluorescent light is as low as a half of that of the fluorescent light. In order to replace the conventional fluorescent light with the LED light, it is sufficient to simply remove the stabilizer and the fluorescent light and to install the LED light.
FIG. 1 is a circuit diagram of an example of a resistance-connected AC-direct-type LED drive circuit.
Although one can only replace a fluorescent light with a resistance-connected LED light, leaving a conventional rapid start stabilizer as installed, as shown in FIG. 1, if the conventional fluorescent light is simply replaced with the LED light, not only the input power factor is degraded, but also a generation of the total harmonic distortion (THD) is increased and it is hard to obtain a desired output power, thus resulting in undesirable output characteristics.